package org.apache.ojb.broker.util.sequence;
   
   /* Copyright 2002-2005 The Apache Software Foundation
    *
    * Licensed under the Apache License, Version 2.0 (the "License");
    * you may not use this file except in compliance with the License.
    * You may obtain a copy of the License at
    *
    *     http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  
  import org.apache.ojb.broker.PersistenceBroker;
  import org.apache.ojb.broker.PersistenceBrokerException;
  import org.apache.ojb.broker.metadata.SequenceDescriptor;
  import org.apache.ojb.broker.util.ClassHelper;
  import org.apache.ojb.broker.util.logging.Logger;
  import org.apache.ojb.broker.util.logging.LoggerFactory;
  
  /**
   * Threadsafe factory class, creates <code>SequenceManager</code> instances.
   * The implementation class is configured by the OJB.properties file.
   */
  public class SequenceManagerFactory
  {
      private static Logger log = LoggerFactory.getLogger(SequenceManagerFactory.class);
      private static SequenceManagerFactory singleton;
  
      private Class defaultSeqManagerClass;
  
      public SequenceManagerFactory()
      {
          defaultSeqManagerClass = SequenceManagerHighLowImpl.class;
          if(log.isDebugEnabled()) log.debug("Default sequence manager class was " + defaultSeqManagerClass.getName());
      }
  
      public synchronized static SequenceManager getSequenceManager(PersistenceBroker broker)
      {
          if (singleton == null)
          {
              singleton = new SequenceManagerFactory();
          }
          return singleton.createNewSequenceManager(broker);
      }
  
      private SequenceManager createNewSequenceManager(PersistenceBroker broker)
      {
          synchronized (singleton)
          {
              if (log.isDebugEnabled()) log.debug("create new sequence manager for broker " + broker);
              try
              {
                  // first we use seqMan defined in the OJB.properties
                  Class seqManClass = defaultSeqManagerClass;
                  SequenceDescriptor sd = broker.serviceConnectionManager().getConnectionDescriptor().getSequenceDescriptor();
                  if (sd != null && sd.getSequenceManagerClass() != null)
                  {
                      // if a seqMan was defined in repository, use that
                      seqManClass = sd.getSequenceManagerClass();
                      if (log.isDebugEnabled())
                      {
                          log.debug("Jdbc-Connection-Descriptor '" +
                                  broker.serviceConnectionManager().getConnectionDescriptor().getJcdAlias() +
                                  "' use sequence manager: " + seqManClass);
                      }
                  }
                  return (SequenceManager) ClassHelper.newInstance(seqManClass, PersistenceBroker.class, broker);
              }
              catch (Exception ex)
              {
                  log.error("Could not create sequence manager for broker " + broker, ex);
                  throw new PersistenceBrokerException(ex);
              }
          }
      }
  }